Mass membrane technology

Overdevest, P. E. M., Proc. 1998 Membrane Technology/Separations Planning Conference, Newton, Mass. (1998) 140... 

Membrane technology covers various chemical technology disciplines, such as material science and technology, mass transport and process design. By manipulating material properties, membranes can be tailor-made for particular separation tasks... 

TNG (Holland) designed a rectangular module (TNO transversal-how membrane module) contaming hollow hbers. The system performs with high mass-transfer coefficients and low-pressure drops. Furthermore, it shows a good scale-up potential. The module is commercialized by XTO Membrane Technology. 

The term membrane technology has encompassed, in recent decades, various mass transfer operations using a thin layer at an interphase. They differ from classical operations of chemical engineering because they were built around materials with original properties acting under the effect of specific driving forces. Today the ideas have evolved, and a more total analysis, integrating in a far better way the process... 

The direct fixation of the biocatalyst to the sensitive surface of the transducer permits the omission of the inactive semipermeable membranes. However, the advantages of the membrane technology are also lost, such as the specificity of permselective layers and the possibility of affecting the dynamic range by variation of the diffusion resistance. Furthermore, the membrane technology has proved to be useful for reloading reusable sensors with enzyme. In contrast, direct enzyme fixation is mainly suited to disposable sensors. This is especially valid for carbon-based electrodes, metal thin layer electrodes printed on ceramic supports, and mass-produced optoelectronic sensors. Field effect transistors may also be envisaged as basic elements of disposable biosensors. 

With the exception of the precoat applications, RVF s do not usually yield absolutely clear filtrate. Although still widely used, rotary vacuum filters are, in some cases, being replaced by membrane separation technology as the method of choice for clarification of fermentation broths and concentrating cell mass. Membranes can yield more complete filtration clarification, but often a wetter cell paste. 

In most of the traditional immobilization procedures,however, the contributions of recent progress in membrane technology have been very limited. The preparation of enzyme membranes on a large scale for industrial processes, in which selective mass transfer across the artificial membranes is combined with specific chemical reactions,wou1d require low membrane cost and standard preparation procedures. Two immobilization procedures have been recently studied in our laboratory, which might accomplish those requirements. Gelled enzyme membranes,involving labile immobilization at the membrane-solution interface, can result... 

In this study, two types of bioreactors were tested for H2 production by purple nonsulliir bacterium using a shift reaction. The main idea was to improve mass transport of gaseous CO into an aqueous bacterial suspension. A simple method of using hoUow fiber membrane technology to enhance mass transfer of CO has proven effective, but is likely too expensive for commercial applications at the present time. Different types of membrane-based... 

Duranceau S.J., Taylor J.S. (1993), Solute charge and molecular weight modeling for prediction of solute mass transfer coefficients, Proc. of AWWA Membrane Technology Conf., Baltimore, Aug 93,243-249. 

Volume 1 covers fluid dynamics, modelling, mixing of one-phase and dispersed two-phase systems, heat and mass transfer. One chapter is concerned about purification and separation focusing on extraction, membrane technology, and capillary electrochromatography. This is rounded off by a description on microstructured reactors and their engineering/design for various applications. 

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